@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&family=Noto+Sans+TC:wght@300;400;500;600;700&display=swap');

:root {
    /* Color Palette - Premium Indigo/Violet Theme */
    --primary: #4f46e5;
    /* Indigo 600 */
    --primary-hover: #4338ca;
    /* Indigo 700 */
    --primary-light: #818cf8;
    /* Indigo 400 */
    --primary-soft: #e0e7ff;
    /* Indigo 100 */

    --secondary: #7c3aed;
    /* Violet 600 */
    --secondary-hover: #6d28d9;
    /* Violet 700 */

    --accent: #f59e0b;
    /* Amber 500 */

    --success: #10b981;
    /* Emerald 500 */
    --success-soft: #d1fae5;
    /* Emerald 100 */

    --danger: #ef4444;
    /* Red 500 */
    --danger-soft: #fee2e2;
    /* Red 100 */

    --warning: #f59e0b;
    /* Amber 500 */
    --warning-soft: #fef3c7;
    /* Amber 100 */

    /* Neutrals */
    --gray-50: #f9fafb;
    --gray-100: #f3f4f6;
    --gray-200: #e5e7eb;
    --gray-300: #d1d5db;
    --gray-400: #9ca3af;
    --gray-500: #6b7280;
    --gray-600: #4b5563;
    --gray-700: #374151;
    --gray-800: #1f2937;
    --gray-900: #111827;

    /* Shadows (Smooth & Layered) */
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);
    --shadow-inner: inset 0 2px 4px 0 rgb(0 0 0 / 0.05);

    /* Radius */
    --radius-sm: 0.375rem;
    --radius: 0.5rem;
    --radius-md: 0.75rem;
    --radius-lg: 1rem;
    --radius-xl: 1.5rem;
    --radius-full: 9999px;

    /* Typography */
    --font-sans: 'Inter', 'Noto Sans TC', system-ui, -apple-system, sans-serif;
}

/* Reset & Base */
*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: var(--font-sans);
    background-color: var(--gray-50);
    color: var(--gray-800);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

a {
    color: inherit;
    text-decoration: none;
    transition: color 0.2s ease;
}

button {
    font-family: inherit;
}

/* ===== Typography ===== */
h1,
h2,
h3,
h4,
h5,
h6 {
    color: var(--gray-900);
    font-weight: 700;
    line-height: 1.25;
    letter-spacing: -0.025em;
}

h1 {
    font-size: 2.5rem;
}

h2 {
    font-size: 2rem;
}

h3 {
    font-size: 1.5rem;
}

p {
    margin-bottom: 1rem;
    color: var(--gray-600);
}

/* ===== Utilities ===== */
.container {
    width: 100%;
    max-width: 1400px;
    margin-left: auto;
    margin-right: auto;
    padding-left: 1.5rem;
    padding-right: 1.5rem;
}

.text-center {
    text-align: center;
}

.text-right {
    text-align: right;
}

.text-primary {
    color: var(--primary);
}

.font-bold {
    font-weight: 700;
}

.mb-4 {
    margin-bottom: 1rem;
}

.mb-8 {
    margin-bottom: 2rem;
}

.gap-4 {
    gap: 1rem;
}

.gap-8 {
    gap: 2rem;
}

.flex {
    display: flex;
}

.flex-col {
    flex-direction: column;
}

.items-center {
    align-items: center;
}

.justify-between {
    justify-content: space-between;
}

.justify-center {
    justify-content: center;
}

.hidden {
    display: none !important;
}

/* ===== Navigation ===== */
.top-nav {
    background: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--gray-200);
    position: sticky;
    top: 0;
    z-index: 50;
    padding: 0.75rem 0;
    transition: all 0.3s ease;
}

.nav-container {
    width: 100%;
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 3.5rem;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--gray-900);
    transition: transform 0.2s;
}

.logo:hover {
    transform: scale(1.02);
}

.logo-icon {
    width: 2.5rem;
    height: 2.5rem;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.25rem;
    box-shadow: 0 4px 6px -1px rgba(79, 70, 229, 0.2);
}

.nav-right {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.nav-stats {
    display: flex;
    gap: 1.5rem;
    padding-right: 1.5rem;
    border-right: 1px solid var(--gray-200);
    margin-right: 0.5rem;
}

.nav-stat {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.nav-stat-value {
    font-weight: 700;
    color: var(--primary);
    font-size: 1.125rem;
    line-height: 1;
}

.nav-stat-label {
    font-size: 0.75rem;
    color: var(--gray-500);
    font-weight: 500;
}

/* Nav Buttons */
.nav-btn,
.user-btn {
    background: var(--gray-100);
    border: 1px solid transparent;
    padding: 0.5rem 1rem;
    border-radius: var(--radius-full);
    color: var(--gray-700);
    font-size: 0.875rem;
    font-weight: 600;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

.nav-btn:hover,
.user-btn:hover {
    background: white;
    box-shadow: var(--shadow-md);
    transform: translateY(-1px);
}

.nav-btn.primary {
    background: var(--primary);
    color: white;
}

.nav-btn.primary:hover {
    background: var(--primary-hover);
    box-shadow: 0 4px 12px rgba(79, 70, 229, 0.3);
}

.user-avatar {
    width: 2rem;
    height: 2rem;
    background: linear-gradient(135deg, var(--secondary), var(--primary));
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.875rem;
    font-weight: 600;
    border: 2px solid white;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

/* User Menu */
.user-menu {
    position: relative;
}

/* Dropdown */
.dropdown {
    position: absolute;
    top: calc(100% + 1rem);
    right: 0;
    background: white;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-xl);
    min-width: 220px;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px) scale(0.95);
    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    z-index: 100;
    border: 1px solid var(--gray-100);
    overflow: hidden;
}

.dropdown.active {
    opacity: 1;
    visibility: visible;
    transform: translateY(0) scale(1);
}

.dropdown-item {
    padding: 0.75rem 1.25rem;
    color: var(--gray-700);
    cursor: pointer;
    transition: all 0.15s;
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-size: 0.875rem;
    font-weight: 500;
}

.dropdown-item:hover {
    background: var(--gray-50);
    color: var(--primary);
    padding-left: 1.5rem;
}

/* ===== Hero Section ===== */
.hero {
    background: linear-gradient(145deg, var(--primary) 0%, var(--secondary) 100%);
    padding: 6rem 1.5rem;
    text-align: center;
    color: white;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    inset: 0;
    background-image:
        radial-gradient(circle at 10% 20%, rgba(255, 255, 255, 0.1) 0%, transparent 20%),
        radial-gradient(circle at 90% 80%, rgba(255, 255, 255, 0.1) 0%, transparent 20%);
    opacity: 0.6;
}

.hero-content {
    position: relative;
    max-width: 800px;
    margin: 0 auto;
    z-index: 10;
}

.hero h1 {
    font-size: 3.5rem;
    font-weight: 800;
    margin-bottom: 1.5rem;
    letter-spacing: -0.05em;
    color: white;
    text-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

.hero p {
    font-size: 1.25rem;
    opacity: 0.9;
    margin-bottom: 3rem;
    color: rgba(255, 255, 255, 0.9);
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.hero-stats {
    display: flex;
    justify-content: center;
    gap: 3rem;
    margin-top: 3rem;
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(8px);
    padding: 1.5rem 3rem;
    border-radius: var(--radius-xl);
    border: 1px solid rgba(255, 255, 255, 0.2);
    display: inline-flex;
}

.hero-stat-value {
    font-size: 2rem;
    font-weight: 700;
}

.hero-stat-label {
    font-size: 0.875rem;
    opacity: 0.8;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

/* ===== Feature Cards & Grid ===== */
.features-section {
    padding: 4rem 1.5rem;
    max-width: 1400px;
    margin: 0 auto;
}

.section-header {
    text-align: center;
    margin-bottom: 4rem;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
    gap: 2rem;
}

.feature-card {
    background: white;
    border-radius: var(--radius-xl);
    overflow: hidden;
    box-shadow: var(--shadow);
    border: 1px solid var(--gray-100);
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    cursor: pointer;
    display: flex;
    flex-direction: column;
    position: relative;
}

.feature-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-xl);
    border-color: var(--primary-light);
}

.feature-card.coming-soon {
    opacity: 0.6;
    filter: grayscale(0.8);
    cursor: default;
}

.feature-card.coming-soon:hover {
    transform: none;
}

.feature-icon {
    height: 180px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 4rem;
    position: relative;
    background-size: cover;
    background-position: center;
}

.feature-icon.translate {
    background: linear-gradient(135deg, #fef3c7, #fbbf24);
    color: #92400e;
}

.feature-icon.vocabulary {
    background: linear-gradient(135deg, #dbeafe, #60a5fa);
    color: #1e40af;
}

.feature-icon.grammar {
    background: linear-gradient(135deg, #d1fae5, #34d399);
    color: #065f46;
}

.feature-icon.listening {
    background: linear-gradient(135deg, #fce7f3, #f472b6);
    color: #9d174d;
}

.feature-icon.reading {
    background: linear-gradient(135deg, #e0e7ff, #818cf8);
    color: #3730a3;
}

.feature-icon.speaking {
    background: linear-gradient(135deg, #ffedd5, #fb923c);
    color: #9a3412;
}

.feature-badge {
    position: absolute;
    top: 1rem;
    right: 1rem;
    background: rgba(0, 0, 0, 0.6);
    backdrop-filter: blur(4px);
    color: white;
    font-size: 0.75rem;
    font-weight: 700;
    padding: 0.25rem 0.75rem;
    border-radius: var(--radius-full);
}

.feature-content {
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    flex: 1;
}

.feature-title {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    color: var(--gray-900);
}

.feature-desc {
    font-size: 0.875rem;
    color: var(--gray-500);
    line-height: 1.6;
    margin-bottom: 1.5rem;
    flex: 1;
}

.feature-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: 1rem;
    border-top: 1px solid var(--gray-100);
}

.feature-stats {
    display: flex;
    gap: 1rem;
    font-size: 0.875rem;
    color: var(--gray-500);
    font-weight: 500;
}

.feature-arrow {
    width: 2.5rem;
    height: 2.5rem;
    border-radius: 50%;
    background: var(--gray-50);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--gray-400);
    transition: all 0.2s;
}

.feature-card:hover .feature-arrow {
    background: var(--primary);
    color: white;
    transform: translateX(4px);
}

/* ===== Content Pages Layout ===== */
.main-layout {
    max-width: 1400px;
    margin: 0 auto;
    padding: 2rem 1.5rem;
    display: grid;
    grid-template-columns: 320px 1fr;
    gap: 2rem;
}

.sidebar {
    position: sticky;
    top: 6rem;
    height: fit-content;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

/* Sidebar Cards */
.sidebar-card {
    background: white;
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    box-shadow: var(--shadow);
    border: 1px solid var(--gray-100);
}

.sidebar-title {
    font-size: 0.75rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--gray-400);
    margin-bottom: 1rem;
}

/* Stats Grid in Sidebar */
.stats-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 0.75rem;
}

.stat-box {
    background: var(--gray-50);
    border-radius: var(--radius);
    padding: 1rem;
    text-align: center;
    border: 1px solid transparent;
    transition: all 0.2s;
}

.stat-box:hover {
    border-color: var(--gray-200);
    background: white;
    box-shadow: var(--shadow-sm);
}

.stat-box .value {
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--gray-900);
    line-height: 1.1;
}

.stat-box .label {
    font-size: 0.75rem;
    color: var(--gray-500);
    margin-top: 0.25rem;
}

.stat-box.success .value {
    color: var(--success);
}

.stat-box.warning .value {
    color: var(--warning);
}

.stat-box.danger .value {
    color: var(--danger);
}

/* Topic List */
.topic-list {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    max-height: 400px;
    overflow-y: auto;
    padding-right: 0.25rem;
}

.topic-list::-webkit-scrollbar {
    width: 4px;
}

.topic-list::-webkit-scrollbar-thumb {
    background: var(--gray-200);
    border-radius: 4px;
}

.topic-item {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.75rem 1rem;
    border-radius: var(--radius);
    cursor: pointer;
    transition: all 0.2s;
    background: white;
    border: 1px solid var(--gray-100);
}

.topic-item:hover {
    border-color: var(--primary-light);
    background: var(--gray-50);
}

.topic-item.selected {
    background: var(--primary-soft);
    border-color: var(--primary);
    color: var(--primary-hover);
}

.topic-item .icon {
    font-size: 1.25rem;
}

.topic-item .name {
    flex: 1;
    font-weight: 500;
    font-size: 0.875rem;
}

.topic-item .count {
    font-size: 0.75rem;
    background: var(--gray-100);
    padding: 0.125rem 0.5rem;
    border-radius: var(--radius-full);
    color: var(--gray-500);
}

.topic-item.selected .count {
    background: white;
    color: var(--primary);
}

/* Difficulty Buttons */
.difficulty-grid {
    display: flex;
    gap: 0.5rem;
}

.diff-btn {
    flex: 1;
    padding: 0.75rem;
    border: 2px solid var(--gray-100);
    border-radius: var(--radius);
    background: white;
    cursor: pointer;
    text-align: center;
    transition: all 0.2s;
}

.diff-btn:hover {
    border-color: var(--primary-soft);
    background: var(--gray-50);
}

.diff-btn.selected {
    border-color: var(--primary);
    background: var(--primary-soft);
}

.diff-btn .level {
    font-size: 1.25rem;
    font-weight: 800;
    color: var(--gray-400);
    transition: color 0.2s;
}

.diff-btn.selected .level {
    color: var(--primary);
}

.diff-btn .label {
    font-size: 0.625rem;
    font-weight: 600;
    text-transform: uppercase;
    color: var(--gray-400);
}

/* ===== Main Content Area ===== */
.main-content {
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

/* Guest Banner */
.guest-banner {
    background: linear-gradient(135deg, #FFFBEB, #FEF3C7);
    border: 1px solid #FCD34D;
    padding: 1.5rem;
    border-radius: var(--radius-lg);
    display: flex;
    align-items: center;
    justify-content: space-between;
    box-shadow: var(--shadow-sm);
}

.guest-banner-text {
    color: #92400e;
}

.guest-banner-text strong {
    display: block;
    font-size: 1rem;
    margin-bottom: 0.25rem;
}

.guest-banner-text span {
    font-size: 0.875rem;
    opacity: 0.8;
}

/* Content Cards */
.content-card {
    background: white;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow);
    border: 1px solid var(--gray-100);
    overflow: hidden;
}

.card-header {
    background: white;
    padding: 1.25rem 1.5rem;
    border-bottom: 1px solid var(--gray-100);
    display: flex;
    align-items: center;
    gap: 1rem;
}

.card-header .step {
    width: 2rem;
    height: 2rem;
    background: var(--primary);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 0.875rem;
    box-shadow: 0 2px 4px rgba(79, 70, 229, 0.3);
}

.card-header .title {
    font-weight: 600;
    color: var(--gray-900);
    font-size: 1rem;
}

.card-body {
    padding: 2rem;
}

/* Question Box */
.question-box {
    background: var(--gray-50);
    border-radius: var(--radius-lg);
    padding: 2.5rem;
    font-size: 1.5rem;
    color: var(--gray-800);
    text-align: center;
    line-height: 1.5;
    border: 1px solid var(--gray-200);
    box-shadow: inset 0 2px 4px rgba(0, 0, 0, 0.02);
    margin-bottom: 1.5rem;
    min-height: 140px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
}

.question-box.empty {
    color: var(--gray-400);
    font-size: 1rem;
}

.question-hint {
    font-size: 0.875rem;
    color: var(--gray-500);
    margin-top: 1rem;
    font-style: italic;
}

/* Inputs & Textareas */
input[type="text"],
input[type="email"],
input[type="password"],
textarea {
    width: 100%;
    padding: 0.875rem 1rem;
    border: 2px solid var(--gray-200);
    border-radius: var(--radius);
    font-size: 1rem;
    transition: all 0.2s;
    background: white;
    color: var(--gray-900);
}

textarea {
    min-height: 120px;
    resize: vertical;
}

input:focus,
textarea:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 4px var(--primary-soft);
}

/* Options (Multiple Choice) */
.options-container {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    margin-top: 1.5rem;
}

.option-btn {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1rem 1.25rem;
    background: white;
    border: 2px solid var(--gray-200);
    border-radius: var(--radius);
    cursor: pointer;
    transition: all 0.2s;
    text-align: left;
    width: 100%;
}

.option-btn:hover:not(:disabled) {
    border-color: var(--primary-light);
    background: var(--gray-50);
}

.option-btn.selected {
    border-color: var(--primary);
    background: var(--primary-soft);
}

.option-btn.correct {
    border-color: var(--success);
    background: var(--success-soft);
}

.option-btn.incorrect {
    border-color: var(--danger);
    background: var(--danger-soft);
}

.option-letter {
    width: 2rem;
    height: 2rem;
    background: var(--gray-100);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 600;
    font-size: 0.875rem;
    color: var(--gray-600);
}

.option-btn.selected .option-letter {
    background: var(--primary);
    color: white;
}

.option-btn.correct .option-letter {
    background: var(--success);
    color: white;
}

.option-btn.incorrect .option-letter {
    background: var(--danger);
    color: white;
}

/* Buttons Generic */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.75rem 1.5rem;
    border-radius: var(--radius);
    font-weight: 600;
    font-size: 1rem;
    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    border: none;
    cursor: pointer;
}

.btn:active {
    transform: scale(0.98);
}

.btn-primary {
    background: var(--primary);
    color: white;
    box-shadow: 0 2px 4px rgba(79, 70, 229, 0.3);
}

.btn-primary:hover {
    background: var(--primary-hover);
    box-shadow: 0 4px 12px rgba(79, 70, 229, 0.4);
    transform: translateY(-1px);
}

.btn-success {
    background: var(--success);
    color: white;
    box-shadow: 0 2px 4px rgba(16, 185, 129, 0.3);
}

.btn-warning {
    background: var(--warning);
    color: white;
    box-shadow: 0 2px 4px rgba(245, 158, 11, 0.3);
}

.btn-secondary {
    background: white;
    border: 1px solid var(--gray-200);
    color: var(--gray-700);
}

.btn-secondary:hover {
    background: var(--gray-50);
    border-color: var(--gray-300);
}

.btn-block {
    width: 100%;
}

.btn-lg {
    padding: 1rem 2rem;
    font-size: 1.125rem;
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none !important;
    box-shadow: none !important;
}

/* Result Box */
.result-box {
    margin-top: 1.5rem;
    padding: 1.5rem;
    border-radius: var(--radius);
    animation: slideUp 0.3s ease-out;
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(10px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.result-box.correct {
    background: var(--success-soft);
    border: 1px solid var(--success);
    color: #064e3b;
}

.result-box.incorrect {
    background: var(--danger-soft);
    border: 1px solid var(--danger);
    color: #7f1d1d;
}

.result-box.partial {
    background: var(--warning-soft);
    border: 1px solid var(--warning);
    color: #78350f;
}

.result-title {
    font-weight: 700;
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

/* Modals */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(15, 23, 42, 0.6);
    backdrop-filter: blur(8px);
    display: none;
    justify-content: center;
    align-items: center;
    z-index: 1000;
}

.modal-overlay.active {
    display: flex;
}

.modal {
    background: white;
    border-radius: var(--radius-lg);
    width: 100%;
    max-width: 420px;
    max-height: 90vh;
    overflow-y: auto;
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
    border: 1px solid rgba(255, 255, 255, 0.1);
    animation: modalSlideIn 0.3s ease;
}

@keyframes modalSlideIn {
    from {
        opacity: 0;
        transform: translateY(-20px) scale(0.95);
    }

    to {
        opacity: 1;
        transform: translateY(0) scale(1);
    }
}

.modal-header {
    background: var(--gray-50);
    padding: 1.25rem 1.5rem;
    border-bottom: 1px solid var(--gray-200);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.modal-header h3 {
    margin: 0;
    font-size: 1.125rem;
}

.modal-close {
    background: none;
    border: none;
    font-size: 1.5rem;
    color: var(--gray-400);
    cursor: pointer;
    padding: 0;
    line-height: 1;
    transition: color 0.2s;
}

.modal-close:hover {
    color: var(--gray-700);
}

.modal-body {
    padding: 1.5rem;
}

.form-group {
    margin-bottom: 1rem;
}

.form-group label {
    display: block;
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--gray-700);
    margin-bottom: 0.5rem;
}

.form-group .hint {
    font-size: 0.75rem;
    color: var(--gray-500);
    margin-top: 0.25rem;
}

.form-error {
    background: var(--danger-soft);
    color: var(--danger);
    padding: 0.75rem;
    border-radius: var(--radius);
    font-size: 0.875rem;
    margin-bottom: 1rem;
}

.tab-content {
    display: none;
}

.tab-content.active {
    display: block;
}

/* Tabs */
.tabs {
    display: flex;
    border-bottom: 2px solid var(--gray-100);
    margin-bottom: 1.5rem;
    gap: 2rem;
}

.tab {
    padding: 1rem 0;
    color: var(--gray-500);
    font-weight: 500;
    cursor: pointer;
    border-bottom: 2px solid transparent;
    margin-bottom: -2px;
    transition: all 0.2s;
}

.tab:hover {
    color: var(--gray-800);
}

.tab.active {
    color: var(--primary);
    border-bottom-color: var(--primary);
}

/* Progress Section */
.progress-section {
    background: white;
    padding: 6rem 1.5rem;
    border-top: 1px solid var(--gray-100);
}

.progress-container {
    max-width: 1400px;
    margin: 0 auto;
}

.progress-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 2rem;
}

.progress-card {
    background: var(--gray-50);
    border-radius: var(--radius-lg);
    padding: 2rem;
    text-align: center;
    border: 1px solid var(--gray-100);
}

.progress-card.highlight {
    background: var(--primary);
    color: white;
    border: none;
    box-shadow: 0 10px 25px -5px rgba(79, 70, 229, 0.4);
}

.progress-card .value {
    font-size: 2.5rem;
    font-weight: 800;
    margin-bottom: 0.5rem;
    color: var(--gray-900);
}

.progress-card.highlight .value {
    color: white;
}

.progress-card .label {
    color: var(--gray-500);
    font-size: 0.875rem;
}

.progress-card.highlight .label {
    color: rgba(255, 255, 255, 0.8);
}

/* Footer */
footer {
    background: white;
    border-top: 1px solid var(--gray-200);
    padding: 3rem 1.5rem;
    text-align: center;
    color: var(--gray-500);
}

/* Mobile Responsive */
@media (max-width: 900px) {
    .main-layout {
        grid-template-columns: 1fr;
    }

    .sidebar {
        position: static;
        order: -1;
    }

    .hero h1 {
        font-size: 2.5rem;
    }

    .progress-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .nav-stats {
        display: none;
    }
}

@media (max-width: 600px) {
    .nav-container {
        padding: 0 1rem;
    }

    .logo>span {
        display: none;
    }

    .logo.logo-home>span {
        display: inline;
    }

    .hero {
        padding: 4rem 1rem;
    }

    .features-grid {
        grid-template-columns: 1fr;
    }

    .progress-grid {
        grid-template-columns: 1fr;
    }

    .question-box {
        padding: 1.5rem;
        font-size: 1.25rem;
    }

    .mode-tabs {
        flex-direction: column;
    }

    .guest-banner {
        flex-direction: column;
        gap: 1rem;
        text-align: center;
    }
}

/* ===== Loading & Spinner ===== */
.loading {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 2.5rem;
    color: var(--gray-500);
}

.spinner {
    width: 2.5rem;
    height: 2.5rem;
    border: 3px solid var(--gray-200);
    border-top-color: var(--primary);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin-bottom: 1rem;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

.loading-text {
    margin-top: 1rem;
    color: var(--gray-500);
}

/* ===== Nav Badge ===== */
.nav-btn {
    position: relative;
}

.nav-btn.has-badge {
    background: linear-gradient(135deg, #ef4444, #dc2626);
    color: white;
}

.nav-badge {
    position: absolute;
    top: -6px;
    right: -6px;
    background: var(--danger);
    color: white;
    font-size: 0.6875rem;
    font-weight: 700;
    min-width: 1.25rem;
    height: 1.25rem;
    border-radius: 0.625rem;
    display: flex;
    align-items: center;
    justify-content: center;
    border: 2px solid white;
}

/* ===== Button Group & Variants ===== */
.btn-group {
    display: flex;
    gap: 0.75rem;
    margin-top: 1.25rem;
}

.btn-discuss {
    background: linear-gradient(135deg, #f59e0b, #d97706);
    color: white;
    border: none;
    padding: 0.625rem 1.25rem;
    border-radius: var(--radius);
    cursor: pointer;
    font-size: 0.875rem;
    font-weight: 500;
    transition: all 0.2s;
}

.btn-discuss:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(245, 158, 11, 0.4);
}

/* ===== Review Modal ===== */
.review-modal {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(4px);
    z-index: 1000;
    justify-content: center;
    align-items: center;
    padding: 1.25rem;
}

.review-modal.active {
    display: flex;
}

.review-modal-content {
    background: white;
    border-radius: var(--radius-xl);
    width: 100%;
    max-width: 700px;
    max-height: 90vh;
    overflow-y: auto;
    box-shadow: var(--shadow-xl);
}

.review-header {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: white;
    padding: 1.5rem 1.75rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.review-header h2 {
    margin: 0;
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-size: 1.25rem;
    color: white;
}

.review-close {
    background: rgba(255, 255, 255, 0.2);
    border: none;
    color: white;
    width: 2.25rem;
    height: 2.25rem;
    border-radius: 50%;
    font-size: 1.25rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s;
}

.review-close:hover {
    background: rgba(255, 255, 255, 0.3);
}

.review-body {
    padding: 1.5rem 1.75rem;
}

.review-info {
    background: linear-gradient(135deg, #d1fae5, #a7f3d0);
    border-radius: var(--radius);
    padding: 1rem 1.25rem;
    margin-bottom: 1.25rem;
}

.review-info h3 {
    color: #065f46;
    margin: 0 0 0.375rem 0;
    font-size: 1rem;
}

.review-info p {
    color: #047857;
    margin: 0;
    font-size: 0.875rem;
}

.review-stats {
    display: flex;
    gap: 0.75rem;
    margin-bottom: 1.25rem;
}

.review-stat {
    flex: 1;
    text-align: center;
    padding: 1rem;
    background: var(--gray-50);
    border-radius: var(--radius);
}

.review-stat .value {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--gray-800);
}

.review-stat .label {
    font-size: 0.75rem;
    color: var(--gray-500);
    margin-top: 0.25rem;
}

.review-stat.urgent {
    background: #fee2e2;
}

.review-stat.urgent .value {
    color: var(--danger);
}

.review-stat.danger .value {
    color: var(--danger);
}

.review-stat.success .value {
    color: var(--success);
}

.review-queue {
    margin-top: 1.25rem;
}

.review-queue-item {
    background: var(--gray-50);
    border: 1px solid var(--gray-200);
    border-radius: var(--radius);
    padding: 0.875rem 1.125rem;
    margin-bottom: 0.625rem;
    cursor: pointer;
    transition: all 0.2s;
}

.review-queue-item:hover {
    background: white;
    border-color: var(--primary);
    box-shadow: var(--shadow);
}

.review-queue-item .question-preview,
.review-queue-item .chinese {
    font-size: 0.875rem;
    color: var(--gray-800);
    margin-bottom: 0.5rem;
    line-height: 1.5;
    font-weight: 500;
}

.review-queue-item .meta {
    display: flex;
    gap: 0.75rem;
    font-size: 0.75rem;
    color: var(--gray-500);
}

.review-queue-item .meta .topic {
    color: var(--primary);
}

.review-queue-item .meta .score {
    color: var(--danger);
}

.review-queue-item .meta .score.good {
    color: var(--success);
}

.empty-review {
    text-align: center;
    padding: 2.5rem;
    color: var(--gray-500);
}

.empty-review .icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

/* Review Practice */
.review-practice .review-question {
    background: linear-gradient(135deg, #fef3c7, #fde68a);
    border-radius: var(--radius);
    padding: 1.25rem;
    font-size: 1rem;
    color: #92400e;
    margin-bottom: 1rem;
    line-height: 1.6;
}

.review-practice .review-options {
    display: flex;
    flex-direction: column;
    gap: 0.625rem;
    margin-bottom: 1rem;
}

.review-practice .review-option {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.75rem 1rem;
    background: white;
    border: 2px solid var(--gray-200);
    border-radius: var(--radius);
    cursor: pointer;
    transition: all 0.2s;
    font-size: 0.875rem;
}

.review-practice .review-option:hover:not(.disabled) {
    border-color: var(--primary-light);
    background: var(--gray-50);
}

.review-practice .review-option.selected {
    border-color: var(--primary);
    background: var(--primary-soft);
}

.review-practice .review-option.correct {
    border-color: var(--success);
    background: var(--success-soft);
}

.review-practice .review-option.incorrect {
    border-color: var(--danger);
    background: var(--danger-soft);
}

.review-practice .review-option.disabled {
    cursor: default;
}

.review-practice .option-letter {
    width: 1.75rem;
    height: 1.75rem;
    background: var(--gray-100);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 600;
    font-size: 0.8125rem;
    color: var(--gray-600);
    flex-shrink: 0;
}

.review-practice .review-option.selected .option-letter {
    background: var(--primary);
    color: white;
}

.review-practice .review-option.correct .option-letter {
    background: var(--success);
    color: white;
}

.review-practice .review-option.incorrect .option-letter {
    background: var(--danger);
    color: white;
}

.review-result {
    background: var(--gray-50);
    border-radius: var(--radius);
    padding: 1rem;
    margin-top: 1rem;
}

.review-result.correct {
    background: var(--success-soft);
    border: 1px solid var(--success);
}

.review-result.incorrect {
    background: var(--danger-soft);
    border: 1px solid var(--danger);
}

.review-result.partial {
    background: var(--warning-soft);
    border: 1px solid var(--warning);
}

.review-actions {
    display: flex;
    gap: 0.75rem;
    margin-top: 1rem;
}

.review-actions .btn {
    flex: 1;
}

.review-result-actions {
    display: flex;
    gap: 0.75rem;
    margin-top: 1.25rem;
}

.review-result-actions .btn {
    flex: 1;
}

/* Review modal variant headers */
.review-modal-header {
    padding: 1.5rem 1.75rem;
    border-bottom: 1px solid var(--gray-100);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.review-modal-title {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--gray-800);
}

.review-close-btn {
    background: var(--gray-100);
    border: none;
    width: 2.25rem;
    height: 2.25rem;
    border-radius: 50%;
    font-size: 1.25rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--gray-600);
    transition: all 0.2s;
}

.review-close-btn:hover {
    background: var(--gray-200);
}

.review-modal-body {
    padding: 1.75rem;
}

.review-empty {
    text-align: center;
    padding: 2.5rem;
    color: var(--gray-400);
}

.review-list {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.review-list-item {
    background: var(--gray-50);
    padding: 1rem;
    border-radius: var(--radius);
    cursor: pointer;
    transition: all 0.2s;
    border: 2px solid transparent;
}

.review-list-item:hover {
    border-color: var(--primary-light);
    background: white;
    box-shadow: var(--shadow);
}

/* Review Input */
.review-question {
    background: linear-gradient(135deg, #fef3c7, #fde68a);
    border-radius: var(--radius);
    padding: 1.5rem;
    font-size: 1.25rem;
    text-align: center;
    color: #92400e;
    margin-bottom: 1.25rem;
    font-weight: 500;
}

.review-previous {
    background: var(--gray-50);
    border-radius: var(--radius-sm);
    padding: 0.875rem 1rem;
    margin-bottom: 1.25rem;
}

.review-previous-label {
    font-size: 0.6875rem;
    color: var(--gray-400);
    margin-bottom: 0.25rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.review-previous-answer {
    color: var(--gray-600);
}

.review-input {
    width: 100%;
    padding: 1rem 1.25rem;
    border: 2px solid var(--gray-200);
    border-radius: var(--radius);
    font-size: 1rem;
    resize: none;
    min-height: 100px;
    margin-bottom: 1.25rem;
    font-family: var(--font-sans);
}

.review-input:focus {
    outline: none;
    border-color: var(--primary);
}

/* Review Discussion */
.review-discussion {
    margin-top: 1.25rem;
    padding-top: 1.25rem;
    border-top: 1px solid var(--gray-200);
}

.review-discussion .chat-messages {
    max-height: 300px;
}

/* ===== Chat / Discussion UI ===== */
.chat-messages {
    max-height: 400px;
    overflow-y: auto;
    padding: 1.25rem;
    background: var(--gray-50);
    border-radius: var(--radius);
    margin-bottom: 1rem;
}

.chat-message {
    margin-bottom: 1rem;
    display: flex;
    gap: 0.75rem;
}

.chat-message.user {
    flex-direction: row-reverse;
}

.chat-avatar {
    width: 2.5rem;
    height: 2.5rem;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1rem;
    flex-shrink: 0;
}

.chat-message.ai .chat-avatar {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: white;
}

.chat-message.user .chat-avatar {
    background: var(--gray-300);
}

.chat-bubble {
    max-width: 80%;
    padding: 0.875rem 1.125rem;
    border-radius: var(--radius-lg);
    line-height: 1.6;
    font-size: 0.875rem;
}

.chat-message.ai .chat-bubble {
    background: white;
    border: 1px solid var(--gray-200);
    border-radius: var(--radius-lg) var(--radius-lg) var(--radius-lg) 4px;
}

.chat-message.user .chat-bubble {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: white;
    border-radius: var(--radius-lg) var(--radius-lg) 4px var(--radius-lg);
}

.chat-input-area {
    display: flex;
    gap: 0.75rem;
}

.chat-input {
    flex: 1;
    padding: 0.875rem 1.25rem;
    border: 2px solid var(--gray-200);
    border-radius: 50px;
    font-size: 0.875rem;
    font-family: var(--font-sans);
    transition: all 0.2s;
}

.chat-input:focus {
    outline: none;
    border-color: var(--primary);
}

.chat-send {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: white;
    border: none;
    width: 3rem;
    height: 3rem;
    border-radius: 50%;
    font-size: 1.25rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s;
}

.chat-send:hover {
    transform: scale(1.1);
}

.chat-send:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none;
}

.quick-questions {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 1rem;
}

.quick-question {
    background: white;
    border: 1px solid var(--primary);
    color: var(--primary);
    padding: 0.5rem 1rem;
    border-radius: 1.25rem;
    font-size: 0.8125rem;
    cursor: pointer;
    transition: all 0.2s;
    font-family: var(--font-sans);
}

.quick-question:hover {
    background: var(--primary);
    color: white;
}

.typing-indicator {
    display: flex;
    gap: 4px;
    padding: 0.875rem 1.125rem;
}

.typing-indicator span {
    width: 8px;
    height: 8px;
    background: var(--gray-400);
    border-radius: 50%;
    animation: typing 1.4s infinite;
}

.typing-indicator span:nth-child(2) {
    animation-delay: 0.2s;
}

.typing-indicator span:nth-child(3) {
    animation-delay: 0.4s;
}

@keyframes typing {

    0%,
    60%,
    100% {
        transform: translateY(0);
    }

    30% {
        transform: translateY(-6px);
    }
}

/* Discussion Toggle */
.discussion-section {
    margin-top: 1.5rem;
    border-top: 1px solid var(--gray-200);
    padding-top: 1.5rem;
}

.discussion-toggle {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.625rem;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: white;
    border: none;
    padding: 0.875rem 1.75rem;
    border-radius: 50px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    width: 100%;
}

.discussion-toggle:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 20px -4px rgba(79, 70, 229, 0.5);
}

.discussion-container {
    margin-top: 1.25rem;
    display: none;
}

.discussion-container.active {
    display: block;
}

/* ===== History Items ===== */
.history-item {
    border: 1px solid var(--gray-200);
    border-radius: var(--radius);
    padding: 1.25rem;
    margin-bottom: 1rem;
    transition: all 0.2s;
}

.history-item:hover {
    border-color: var(--primary-light);
    box-shadow: var(--shadow);
}

.history-item .header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 0.75rem;
}

.history-item .topic {
    font-size: 0.8125rem;
    color: var(--gray-500);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.history-item .score {
    font-weight: 600;
    padding: 0.25rem 0.75rem;
    border-radius: 1.25rem;
    font-size: 0.875rem;
}

.history-item .score.correct {
    background: #d1fae5;
    color: #065f46;
}

.history-item .score.partial {
    background: #fef3c7;
    color: #92400e;
}

.history-item .score.incorrect {
    background: #fee2e2;
    color: #991b1b;
}

.history-item .chinese {
    font-size: 1.1rem;
    color: var(--gray-800);
    margin-bottom: 0.75rem;
    font-weight: 500;
}

.history-item .answer {
    font-size: 0.875rem;
    color: var(--gray-600);
    padding: 0.625rem 0.875rem;
    background: var(--gray-50);
    border-radius: var(--radius-sm);
    margin-bottom: 0.5rem;
}

.history-item .answer-label {
    font-size: 0.6875rem;
    color: var(--gray-400);
    margin-bottom: 0.25rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.history-item .answer.suggested {
    background: #d1fae5;
    color: #065f46;
}

.history-item .feedback {
    font-size: 0.8125rem;
    color: var(--gray-600);
    padding: 0.75rem 0.875rem;
    background: var(--gray-50);
    border-left: 3px solid var(--gray-300);
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
    margin-top: 0.75rem;
    line-height: 1.6;
}

.history-item-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 1rem;
    padding-top: 1rem;
    border-top: 1px solid var(--gray-100);
}

.history-item .time {
    font-size: 0.75rem;
    color: var(--gray-400);
}

.history-item .difficulty-badge {
    font-size: 0.6875rem;
    padding: 0.125rem 0.5rem;
    border-radius: 0.625rem;
    background: #dbeafe;
    color: #1d4ed8;
}

.btn-review-this {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: white;
    border: none;
    padding: 0.5rem 1rem;
    border-radius: 1.25rem;
    font-size: 0.8125rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s;
}

.btn-review-this:hover {
    transform: scale(1.05);
    box-shadow: 0 4px 12px rgba(79, 70, 229, 0.4);
}

.no-history {
    text-align: center;
    color: var(--gray-400);
    padding: 3.75rem 1.25rem;
}

/* ===== Result Variants ===== */
.result-score {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 0.75rem;
}

.result-explanation {
    color: var(--gray-700);
    line-height: 1.8;
}

.result-explanation strong {
    color: var(--gray-800);
}

.result-stats {
    margin-top: 1rem;
    font-size: 0.75rem;
    color: var(--gray-400);
    text-align: right;
}

.result-box.empty {
    background: var(--gray-50);
    color: var(--gray-400);
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
}

.suggested-answer {
    margin-top: 1.25rem;
    padding: 1.25rem;
    background: var(--gray-50);
    border-radius: var(--radius);
}

.suggested-answer label {
    font-weight: 600;
    color: var(--gray-600);
    display: block;
    margin-bottom: 0.5rem;
    font-size: 0.8125rem;
}

.suggested-answer .answer {
    font-size: 1.1rem;
    color: var(--gray-800);
    font-style: italic;
}

/* Next Button Group */
.next-btn-group {
    margin-top: 1.25rem;
    display: flex;
    gap: 0.75rem;
    flex-wrap: wrap;
}

/* ===== Mastery Indicator ===== */
.mastery-indicator {
    display: flex;
    gap: 4px;
    margin-top: 0.5rem;
}

.mastery-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: var(--gray-200);
}

.mastery-dot.filled {
    background: var(--success);
}

/* ===== Modal Large Variant ===== */
.modal.modal-large {
    max-width: 800px;
}

/* ===== Vocabulary / Flashcard Styles ===== */
.main-container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 2.5rem;
    display: grid;
    grid-template-columns: 320px 1fr;
    gap: 2rem;
}

/* Vocab Stats */
.stat-item {
    background: var(--gray-50);
    border-radius: var(--radius);
    padding: 1rem;
    text-align: center;
    transition: all 0.2s;
}

.stat-item:hover {
    background: var(--gray-100);
}

.stat-value {
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--primary);
    line-height: 1.2;
}

.stat-label {
    font-size: 0.75rem;
    color: var(--gray-500);
    margin-top: 0.25rem;
}

.stat-item.highlight {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    grid-column: span 2;
}

.stat-item.highlight .stat-value,
.stat-item.highlight .stat-label {
    color: white;
}

/* Category List */
.category-list {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.category-item {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.75rem 1rem;
    border-radius: var(--radius);
    cursor: pointer;
    transition: all 0.2s;
    background: var(--gray-50);
}

.category-item:hover {
    background: var(--gray-100);
}

.category-item.active {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: white;
}

.category-icon {
    font-size: 1.25rem;
}

.category-name {
    flex: 1;
    font-weight: 500;
}

.category-count {
    font-size: 0.75rem;
    padding: 0.125rem 0.5rem;
    background: rgba(0, 0, 0, 0.1);
    border-radius: 0.625rem;
}

.category-item.active .category-count {
    background: rgba(255, 255, 255, 0.2);
}

/* Difficulty List */
.difficulty-list {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.diff-btn.active {
    border-color: var(--primary);
    background: var(--primary);
    color: white;
}

/* Mode Tabs */
.mode-tabs {
    display: flex;
    gap: 0.75rem;
    background: white;
    padding: 0.5rem;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow);
}

.mode-tab {
    flex: 1;
    padding: 0.875rem 1.25rem;
    border: none;
    background: transparent;
    border-radius: var(--radius);
    cursor: pointer;
    font-size: 0.9375rem;
    font-weight: 500;
    color: var(--gray-600);
    transition: all 0.2s;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    font-family: var(--font-sans);
}

.mode-tab:hover {
    background: var(--gray-50);
}

.mode-tab.active {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: white;
}

/* Flashcard */
.flashcard-area {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: flex-start;
    padding: 1.25rem;
}

.flashcard-container {
    perspective: 1000px;
    width: 100%;
    max-width: 500px;
    height: 320px;
}

.flashcard {
    width: 100%;
    height: 100%;
    position: relative;
    transform-style: preserve-3d;
    transition: transform 0.6s;
    cursor: pointer;
}

.flashcard.flipped {
    transform: rotateY(180deg);
}

.flashcard-face {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-xl);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 2rem;
    text-align: center;
}

.flashcard-front {
    background: linear-gradient(135deg, #dbeafe, #bfdbfe);
}

.flashcard-back {
    background: white;
    transform: rotateY(180deg);
}

.word-text {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--gray-800);
    margin-bottom: 0.75rem;
}

.word-phonetic {
    font-size: 1.25rem;
    color: var(--gray-500);
    margin-bottom: 0.5rem;
}

.word-pos {
    font-size: 0.875rem;
    color: white;
    background: var(--primary);
    padding: 0.25rem 0.75rem;
    border-radius: 1.25rem;
}

.word-definition {
    font-size: 1.5rem;
    color: var(--gray-800);
    margin-bottom: 1rem;
}

.word-example {
    font-size: 0.875rem;
    color: var(--gray-600);
    font-style: italic;
    max-width: 400px;
    line-height: 1.6;
}

.word-example-zh {
    font-size: 0.8125rem;
    color: var(--gray-500);
    margin-top: 0.5rem;
    font-style: normal;
}

.flip-hint {
    position: absolute;
    bottom: 1rem;
    font-size: 0.75rem;
    color: var(--gray-400);
}

/* Quiz Options */
.quiz-options {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 0.75rem;
    width: 100%;
    max-width: 500px;
    margin-top: 1.5rem;
}

.quiz-option {
    padding: 1rem 1.25rem;
    border: 2px solid var(--gray-200);
    border-radius: var(--radius-lg);
    background: white;
    font-size: 0.9375rem;
    font-weight: 500;
    color: var(--gray-700);
    cursor: pointer;
    transition: all 0.2s;
    text-align: center;
    font-family: var(--font-sans);
}

.quiz-option:hover {
    border-color: var(--primary-light);
    background: var(--gray-50);
    transform: translateY(-2px);
}

.quiz-option.selected {
    border-color: var(--primary);
    background: rgba(79, 70, 229, 0.1);
}

.quiz-option.correct {
    border-color: var(--success);
    background: #ecfdf5;
    color: var(--success);
}

.quiz-option.wrong {
    border-color: var(--danger);
    background: #fef2f2;
    color: var(--danger);
}

.quiz-option:disabled {
    cursor: not-allowed;
    opacity: 0.7;
}

/* Answer Feedback */
.answer-feedback {
    margin-top: 1.25rem;
    padding: 1rem 1.5rem;
    border-radius: var(--radius-lg);
    text-align: center;
    font-weight: 500;
}

.answer-feedback.correct {
    background: #ecfdf5;
    color: var(--success);
    border: 1px solid #a7f3d0;
}

.answer-feedback.wrong {
    background: #fef2f2;
    color: var(--danger);
    border: 1px solid #fecaca;
}

.answer-feedback.removed {
    background: #fef3c7;
    color: #d97706;
    border: 1px solid #fcd34d;
}

.answer-feedback .correct-answer {
    margin-top: 0.5rem;
    font-size: 0.875rem;
    color: var(--gray-600);
}

.consecutive-progress {
    margin-top: 1rem;
    padding: 0.625rem 1.25rem;
    background: linear-gradient(135deg, #f0f9ff, #e0f2fe);
    border: 1px solid #bae6fd;
    border-radius: var(--radius);
    font-size: 0.875rem;
    color: var(--gray-600);
    text-align: center;
}

.consecutive-progress .count {
    font-weight: 700;
    font-size: 1rem;
    color: var(--primary);
}

/* Next Button (vocab) */
.next-btn {
    margin-top: 1.25rem;
    padding: 0.875rem 2rem;
    border: none;
    border-radius: var(--radius-lg);
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: white;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    font-family: var(--font-sans);
}

.next-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(79, 70, 229, 0.4);
}

/* Progress Bar */
.progress-bar {
    width: 100%;
    max-width: 500px;
    height: 8px;
    background: var(--gray-200);
    border-radius: 4px;
    margin-top: 1.5rem;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--primary), var(--secondary));
    border-radius: 4px;
    transition: width 0.3s;
}

.progress-text {
    font-size: 0.8125rem;
    color: var(--gray-500);
    margin-top: 0.5rem;
}

/* Empty State */
.empty-state {
    text-align: center;
    padding: 3.75rem 1.25rem;
}

.empty-state .icon {
    font-size: 4rem;
    margin-bottom: 1.25rem;
}

.empty-state h3 {
    font-size: 1.5rem;
    color: var(--gray-700);
    margin-bottom: 0.75rem;
}

.empty-state p {
    color: var(--gray-500);
    margin-bottom: 1.5rem;
}

/* Word List */
.word-list {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    padding: 1.25rem;
}

.word-list-item {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1rem 1.25rem;
    background: white;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    cursor: pointer;
    transition: all 0.2s;
}

.word-list-item:hover {
    transform: translateX(4px);
    box-shadow: var(--shadow-lg);
}

.word-list-text {
    flex: 1;
}

.word-list-text h4 {
    font-size: 1.1rem;
    color: var(--gray-800);
    margin-bottom: 0.25rem;
}

.word-list-text p {
    font-size: 0.875rem;
    color: var(--gray-500);
}

.word-list-meta {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.favorite-btn {
    background: none;
    border: none;
    font-size: 1.25rem;
    cursor: pointer;
    opacity: 0.3;
    transition: all 0.2s;
}

.favorite-btn:hover,
.favorite-btn.active {
    opacity: 1;
}

/* ===== Speaking / Recording Styles ===== */
.type-list {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.type-item {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.75rem 1rem;
    background: var(--gray-50);
    border: 2px solid transparent;
    border-radius: var(--radius);
    cursor: pointer;
    transition: all 0.2s;
}

.type-item:hover {
    background: var(--gray-100);
    border-color: var(--gray-300);
}

.type-item.selected {
    background: var(--primary-soft);
    border-color: var(--primary);
}

.type-item .icon {
    font-size: 1.25rem;
}

.type-item .info {
    flex: 1;
}

.type-item .name {
    font-weight: 500;
    color: var(--gray-700);
}

.type-item .desc {
    font-size: 0.75rem;
    color: var(--gray-500);
}

/* API Warning */
.api-warning {
    background: linear-gradient(135deg, #fef3c7, #fde68a);
    border: 1px solid #fcd34d;
    border-radius: var(--radius);
    padding: 1rem 1.25rem;
    margin-bottom: 1.25rem;
    color: #92400e;
    font-size: 0.875rem;
}

/* Prompt Box (Speaking) */
.prompt-box {
    background: linear-gradient(135deg, var(--gray-50), var(--gray-100));
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    min-height: 120px;
}

.prompt-box.empty {
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--gray-400);
}

.prompt-label {
    font-size: 0.75rem;
    color: var(--gray-500);
    margin-bottom: 0.5rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.prompt-text {
    font-size: 1.25rem;
    line-height: 1.8;
    color: var(--gray-800);
}

.prompt-text .highlight {
    background: linear-gradient(135deg, rgba(79, 70, 229, 0.2), rgba(124, 58, 237, 0.2));
    padding: 0.125rem 0.375rem;
    border-radius: 4px;
}

.prompt-translation {
    margin-top: 0.75rem;
    padding-top: 0.75rem;
    border-top: 1px dashed var(--gray-300);
    font-size: 0.875rem;
    color: var(--gray-600);
}

.listen-btn {
    margin-top: 1rem;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: white;
    border: none;
    padding: 0.625rem 1.25rem;
    border-radius: 50px;
    font-size: 0.875rem;
    cursor: pointer;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    transition: all 0.2s;
}

.listen-btn:hover {
    transform: scale(1.05);
}

.listen-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none;
}

/* Recording Section */
.recording-section {
    text-align: center;
    padding: 2.5rem 1.25rem;
}

.mic-btn {
    width: 120px;
    height: 120px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    border: none;
    color: white;
    font-size: 3rem;
    cursor: pointer;
    transition: all 0.3s;
    box-shadow: 0 8px 32px -4px rgba(79, 70, 229, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto;
}

.mic-btn:hover:not(:disabled) {
    transform: scale(1.1);
    box-shadow: 0 12px 40px -4px rgba(79, 70, 229, 0.6);
}

.mic-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.mic-btn.recording {
    background: linear-gradient(135deg, #ef4444, #dc2626);
    animation: pulse-recording 1.5s infinite;
}

@keyframes pulse-recording {

    0%,
    100% {
        transform: scale(1);
        box-shadow: 0 8px 32px -4px rgba(239, 68, 68, 0.5);
    }

    50% {
        transform: scale(1.05);
        box-shadow: 0 12px 40px -4px rgba(239, 68, 68, 0.7);
    }
}

.recording-status {
    margin-top: 1.25rem;
    font-size: 0.875rem;
    color: var(--gray-600);
}

.recording-status.active {
    color: var(--danger);
    font-weight: 600;
}

.recording-timer {
    font-size: 2rem;
    font-weight: 700;
    color: var(--primary);
    margin-top: 0.75rem;
}

/* Transcript Box */
.transcript-box {
    margin-top: 1.5rem;
    padding: 1.25rem;
    background: var(--gray-50);
    border-radius: var(--radius);
    min-height: 80px;
}

.transcript-label {
    font-size: 0.75rem;
    color: var(--gray-500);
    margin-bottom: 0.5rem;
}

.transcript-text {
    font-size: 1.1rem;
    line-height: 1.8;
    color: var(--gray-800);
}

.transcript-text.empty {
    color: var(--gray-400);
    font-style: italic;
}

/* Speaking Result Variants */
.result-box.excellent {
    background: linear-gradient(135deg, rgba(16, 185, 129, 0.1), rgba(5, 150, 105, 0.1));
    border: 1px solid var(--success);
}

.result-box.good {
    background: linear-gradient(135deg, rgba(79, 70, 229, 0.1), rgba(124, 58, 237, 0.1));
    border: 1px solid var(--primary);
}

.result-box.needs-improvement {
    background: linear-gradient(135deg, rgba(245, 158, 11, 0.1), rgba(217, 119, 6, 0.1));
    border: 1px solid var(--warning);
}

.result-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 1rem;
}

.result-box.excellent .result-title {
    color: var(--success);
}

.result-box.good .result-title {
    color: var(--primary);
}

.result-box.needs-improvement .result-title {
    color: var(--warning);
}

.result-detail {
    font-size: 0.875rem;
    line-height: 1.8;
    color: var(--gray-700);
}

.result-comparison {
    margin-top: 1rem;
    padding: 1rem;
    background: white;
    border-radius: var(--radius-sm);
}

.comparison-row {
    display: flex;
    gap: 0.75rem;
    margin-bottom: 0.5rem;
}

.comparison-row:last-child {
    margin-bottom: 0;
}

.comparison-label {
    width: 60px;
    font-size: 0.75rem;
    color: var(--gray-500);
    flex-shrink: 0;
}

.comparison-text {
    flex: 1;
    font-size: 0.875rem;
}

.comparison-text.correct {
    color: var(--success);
}

.comparison-text.user {
    color: var(--primary);
}

.word-correct {
    color: var(--success);
}

.word-wrong {
    color: var(--danger);
    text-decoration: line-through;
}

.word-missing {
    color: var(--warning);
    opacity: 0.6;
}

/* ===== Content Page Responsive (Override/Extend) ===== */
@media (max-width: 1024px) {

    .main-layout,
    .main-container {
        grid-template-columns: 1fr;
        padding: 1.25rem;
    }

    .sidebar {
        display: grid;
        grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
        gap: 1rem;
    }
}

@media (max-width: 900px) {
    .main-container {
        grid-template-columns: 1fr;
        padding: 1rem;
    }

    .main-container .sidebar {
        display: none;
    }

    .flashcard-container {
        height: 280px;
    }

    .word-text {
        font-size: 2rem;
    }
}

@media (max-width: 768px) {
    .top-nav {
        padding: 0 1rem;
    }
}

/* ===== Listening Page - Audio Player ===== */
.audio-player {
    background: linear-gradient(135deg, var(--gray-50), var(--gray-100));
    border-radius: var(--radius-lg);
    padding: 2rem;
    text-align: center;
    min-height: 200px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
}

.audio-player.empty {
    color: var(--gray-400);
}

.play-btn {
    width: 80px;
    height: 80px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    border: none;
    color: white;
    font-size: 2rem;
    cursor: pointer;
    transition: all 0.3s;
    box-shadow: 0 8px 24px -4px rgba(79, 70, 229, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
}

.play-btn:hover {
    transform: scale(1.1);
    box-shadow: 0 12px 32px -4px rgba(79, 70, 229, 0.6);
}

.play-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none;
}

.play-btn.playing {
    animation: pulse 1.5s infinite;
}

@keyframes pulse {

    0%,
    100% {
        transform: scale(1);
    }

    50% {
        transform: scale(1.05);
    }
}

.audio-info {
    margin-top: 1.25rem;
    font-size: 0.875rem;
    color: var(--gray-600);
}

.audio-text {
    margin-top: 1rem;
    padding: 1rem 1.5rem;
    background: white;
    border-radius: var(--radius);
    font-size: 1.1rem;
    line-height: 1.8;
    color: var(--gray-800);
    max-width: 600px;
    border: 1px solid var(--gray-200);
}

.audio-text.blurred {
    filter: blur(8px);
    user-select: none;
}

.play-count {
    margin-top: 0.75rem;
    font-size: 0.8125rem;
    color: var(--gray-500);
}

.play-count span {
    color: var(--primary);
    font-weight: 600;
}

/* Speed Slider */
.speed-slider {
    padding: 0.5rem 0;
}

.speed-slider input[type="range"] {
    width: 100%;
    height: 6px;
    border-radius: 3px;
    background: var(--gray-200);
    outline: none;
    -webkit-appearance: none;
    appearance: none;
}

.speed-slider input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    cursor: pointer;
    box-shadow: var(--shadow);
}

.speed-labels {
    display: flex;
    justify-content: space-between;
    font-size: 0.75rem;
    color: var(--gray-500);
    margin-top: 0.5rem;
}

.speed-current {
    text-align: center;
    font-weight: 600;
    color: var(--primary);
    margin-top: 0.5rem;
}

/* ===== Listening / Grammar - Answer Section ===== */
.answer-section {
    margin-top: 1.5rem;
}

.answer-label {
    font-weight: 600;
    color: var(--gray-700);
    margin-bottom: 0.75rem;
}

.answer-input {
    width: 100%;
    padding: 1rem 1.25rem;
    border: 2px solid var(--gray-200);
    border-radius: var(--radius);
    font-size: 1rem;
    font-family: var(--font-sans);
    transition: all 0.2s;
    resize: vertical;
    min-height: 100px;
}

.answer-input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 4px rgba(79, 70, 229, 0.1);
}

.answer-input:disabled {
    background: var(--gray-50);
}

/* ===== Listening - Options ===== */
.options-container {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    margin-top: 1rem;
}

.option-item {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 1rem 1.25rem;
    background: var(--gray-50);
    border: 2px solid transparent;
    border-radius: var(--radius);
    cursor: pointer;
    transition: all 0.2s;
}

.option-item:hover:not(.disabled) {
    background: var(--gray-100);
    border-color: var(--gray-300);
}

.option-item.selected {
    border-color: var(--primary);
    background: linear-gradient(135deg, rgba(79, 70, 229, 0.1), rgba(124, 58, 237, 0.1));
}

.option-item.correct {
    border-color: var(--success);
    background: linear-gradient(135deg, rgba(16, 185, 129, 0.1), rgba(5, 150, 105, 0.1));
}

.option-item.incorrect {
    border-color: var(--danger);
    background: linear-gradient(135deg, rgba(239, 68, 68, 0.1), rgba(220, 38, 38, 0.1));
}

.option-item.disabled {
    cursor: default;
}

.option-letter {
    width: 2rem;
    height: 2rem;
    background: var(--gray-200);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 600;
    color: var(--gray-600);
    flex-shrink: 0;
}

.option-item.selected .option-letter {
    background: var(--primary);
    color: white;
}

.option-item.correct .option-letter {
    background: var(--success);
    color: white;
}

.option-item.incorrect .option-letter {
    background: var(--danger);
    color: white;
}

.option-text {
    flex: 1;
    font-size: 1rem;
}

/* Correct Answer Display */
.correct-answer {
    margin-top: 0.75rem;
    padding: 0.75rem 1rem;
    background: white;
    border-radius: var(--radius-sm);
    border-left: 3px solid var(--primary);
}

.correct-answer-label {
    font-size: 0.75rem;
    color: var(--gray-500);
    margin-bottom: 0.25rem;
}

.correct-answer-text {
    font-size: 1rem;
    color: var(--gray-800);
    font-weight: 500;
}

/* ===== Reading Page - Passage ===== */
.passage-box {
    background: var(--gray-50);
    border-radius: var(--radius);
    padding: 1.5rem;
    font-size: 1rem;
    line-height: 2;
    color: var(--gray-800);
    min-height: 200px;
    max-height: 400px;
    overflow-y: auto;
}

.passage-box.empty {
    color: var(--gray-400);
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 200px;
}

.passage-box .passage-title {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--gray-900);
    margin-bottom: 1rem;
    padding-bottom: 0.75rem;
    border-bottom: 2px solid var(--primary-light);
}

.passage-meta {
    display: flex;
    gap: 1rem;
    margin-top: 1rem;
    padding-top: 1rem;
    border-top: 1px solid var(--gray-200);
    font-size: 0.8125rem;
    color: var(--gray-500);
}

.passage-meta span {
    display: flex;
    align-items: center;
    gap: 0.375rem;
}

/* ===== Reading Page - Questions ===== */
.questions-container {
    margin-top: 1.5rem;
}

.question-item {
    background: white;
    border: 1px solid var(--gray-200);
    border-radius: var(--radius);
    padding: 1.25rem;
    margin-bottom: 1rem;
}

.question-item.answered.correct {
    border-color: var(--success);
    background: linear-gradient(135deg, rgba(16, 185, 129, 0.05), rgba(5, 150, 105, 0.05));
}

.question-item.answered.incorrect {
    border-color: var(--danger);
    background: linear-gradient(135deg, rgba(239, 68, 68, 0.05), rgba(220, 38, 38, 0.05));
}

.question-number {
    font-weight: 700;
    color: var(--primary);
    margin-bottom: 0.5rem;
}

.question-text {
    font-size: 1rem;
    color: var(--gray-800);
    margin-bottom: 1rem;
    line-height: 1.6;
}

.question-options {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.question-option {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.75rem 1rem;
    background: var(--gray-50);
    border: 2px solid transparent;
    border-radius: var(--radius);
    cursor: pointer;
    transition: all 0.2s;
    font-size: 0.875rem;
}

.question-option:hover:not(.disabled) {
    background: var(--gray-100);
    border-color: var(--gray-300);
}

.question-option.selected {
    border-color: var(--primary);
    background: linear-gradient(135deg, rgba(79, 70, 229, 0.1), rgba(124, 58, 237, 0.1));
}

.question-option.correct {
    border-color: var(--success);
    background: linear-gradient(135deg, rgba(16, 185, 129, 0.1), rgba(5, 150, 105, 0.1));
}

.question-option.incorrect {
    border-color: var(--danger);
    background: linear-gradient(135deg, rgba(239, 68, 68, 0.1), rgba(220, 38, 38, 0.1));
}

.question-option.disabled {
    cursor: default;
}

.question-option .option-letter {
    width: 1.75rem;
    height: 1.75rem;
    font-size: 0.8125rem;
}

.question-option.selected .option-letter {
    background: var(--primary);
    color: white;
}

.question-option.correct .option-letter {
    background: var(--success);
    color: white;
}

.question-option.incorrect .option-letter {
    background: var(--danger);
    color: white;
}

.question-explanation {
    margin-top: 0.75rem;
    padding: 0.75rem 1rem;
    background: var(--gray-50);
    border-radius: var(--radius);
    font-size: 0.875rem;
    line-height: 1.6;
    color: var(--gray-700);
    border-left: 3px solid var(--primary);
}

/* ===== Reading Page - Result Summary ===== */
.result-summary {
    padding: 1.5rem;
    border-radius: var(--radius);
    margin-top: 1.25rem;
    text-align: center;
}

.result-summary.excellent {
    background: linear-gradient(135deg, rgba(16, 185, 129, 0.1), rgba(5, 150, 105, 0.1));
    border: 1px solid var(--success);
}

.result-summary.good {
    background: linear-gradient(135deg, rgba(79, 70, 229, 0.1), rgba(124, 58, 237, 0.1));
    border: 1px solid var(--primary);
}

.result-summary.needs-improvement {
    background: linear-gradient(135deg, rgba(245, 158, 11, 0.1), rgba(217, 119, 6, 0.1));
    border: 1px solid var(--warning);
}

.result-summary.excellent .result-title {
    color: var(--success);
}

.result-summary.good .result-title {
    color: var(--primary);
}

.result-summary.needs-improvement .result-title {
    color: var(--warning);
}

/* ===== Shared Content Page Components ===== */

/* Topic List (Grammar, Reading sidebar) */
.topic-list {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    max-height: 400px;
    overflow-y: auto;
}

.topic-item {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.75rem 1rem;
    background: var(--gray-50);
    border: 2px solid transparent;
    border-radius: var(--radius);
    cursor: pointer;
    transition: all 0.2s;
}

.topic-item:hover {
    background: var(--gray-100);
    border-color: var(--gray-300);
}

.topic-item.selected {
    background: linear-gradient(135deg, rgba(79, 70, 229, 0.1), rgba(124, 58, 237, 0.1));
    border-color: var(--primary);
}

.topic-item .icon {
    font-size: 1.25rem;
}

.topic-item .name {
    flex: 1;
    font-weight: 500;
    color: var(--gray-700);
}

/* Difficulty Grid (Listening, Reading, Speaking sidebar) */
.difficulty-grid {
    display: flex;
    gap: 0.5rem;
}

.diff-btn {
    flex: 1;
    padding: 0.75rem 0.5rem;
    border: 2px solid var(--gray-200);
    background: white;
    border-radius: var(--radius);
    cursor: pointer;
    transition: all 0.2s;
    text-align: center;
}

.diff-btn:hover {
    border-color: var(--primary-light);
    background: var(--gray-50);
}

.diff-btn.selected {
    border-color: var(--primary);
    background: linear-gradient(135deg, rgba(79, 70, 229, 0.1), rgba(124, 58, 237, 0.1));
}

.diff-btn .level {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--primary);
}

.diff-btn .label {
    font-size: 0.6875rem;
    color: var(--gray-500);
    margin-top: 0.125rem;
}

/* Content Card (Listening, Reading, Speaking) */
.content-card {
    background: white;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow);
    border: 1px solid var(--gray-200);
    overflow: hidden;
}

.card-header {
    padding: 1.25rem 1.75rem;
    border-bottom: 1px solid var(--gray-100);
    display: flex;
    align-items: center;
    gap: 1rem;
}

.card-header .step {
    width: 2rem;
    height: 2rem;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 0.875rem;
}

.card-header .title {
    font-weight: 600;
    color: var(--gray-800);
}

.card-body {
    padding: 1.75rem;
}

/* Guest Banner (shared) */
.guest-banner {
    background: linear-gradient(135deg, #fef3c7, #fde68a);
    border-radius: var(--radius-lg);
    padding: 1.25rem 1.75rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    border: 1px solid #fcd34d;
}

.guest-banner-text {
    color: #92400e;
}

.guest-banner-text strong {
    display: block;
    font-size: 1rem;
    margin-bottom: 0.25rem;
}

.guest-banner-text span {
    font-size: 0.875rem;
    opacity: 0.8;
}